Biology Research

DUE: SUNDAY AUGUST 18 8PM EST

In 1982, Stanley Prusiner, a biomedical researcher at the University of California–San Francisco, dropped a bombshell by proposing in a research paper that proteins can cause disease. Dr. Prusiner was initially skeptical of his own results, as his initial hypotheses revolved around a new type of virus—not a protein—as the cause of the neurological disease he studied. The disease, called scrapie, is similar to mad cow disease and its equivalent in humans, Creutzfeldt–Jakob disease. These diseases are not curable and result in death of cells in the brain. Dr. Prusiner’s proposition was extremely controversial, since most biologists believed all pathogens used DNA or RNA, not protein, as the basis for reproducing and spreading.

Though Dr. Prusiner received intense criticism and personal attacks, his lab eventually isolated the protein that nearly all biologists now agree is the causative agent of scrapie and other similar brain diseases. The characterization of this protein, called a prion, resulted in Dr. Prusiner being awarded the Nobel Prize in medicine. Prions cause disease due to their misfolded structures. Inside the body, prions create abnormal clumps in the brain, characterized by pleated sheets. Since infectious prions may be transmitted by food, careful regulations have been put in place to make sure the nervous systems of cows and other livestock are not used for food. Infectious prions may also be sterilized in tissue through protein hydrolysis and the application of strong acids or bases.

Questions

1. Describe the chemical makeup of prions: What types of monomers are found in a prion? What level of protein structure is described by the pleated sheets that prions form? What types of chemical bonds form the “backbone” of the prion versus the folding pattern of

the prion?

2. Propose chemical explanations for how the sterilization techniques might neutralize

infectious prions. For example, how would hydrolysis affect the chemical bonds of the

prion? How would this compare to the application of acids or bases?

3. What other types of sterilization techniques might you suggest for eliminating

harmful prions?